[ger21]

Double the width of the gantry sides at the base.

Reduce the height of the gantry sides and Z plate by about 1/3 (at least)

Make the gantry from a single beam, or at least tie the two together with a plate.

[vakeiros]

well, if I reduce the gantry height I'll lose Z movement, I have about 250mm right now and I didn't want to have less than that... On the gantry base do you mean on get the base larger or increase the space between the linear blocks? this way I'll loose Y movement and I'm on my limit (Will need bigger rails...)

about the: Make the gantry from a single beam, or at least tie the two together with a plate.

I didn't understood What you meant.

my current overall dimensions are: 700mm height (on gantry side plates), 1380mm length and 800mm width.
my current travell dimensions are: X 530mm, Y 870mm Z 250mm

thanks for the input

[vakeiros]

well guys, new version od the machine with some changes (thanks to Ger21), still missing the steel tubes reinforcing the side pilars on the gantry and lots of bolts missing, this is just to show the project.

any more tips? I had the increase the Y guides from 1000mm to 1150mm because of the new gantry base dimensions (I think this will cost me more $50-60 on the linear rails alone).

so on project:

4x Wantai Nema23 270 Oz/in
2x 1000mm 1610 ballscrews, 2x 1150mm Hiwin 15mm rails for Y axis
1x 650mm 1610 ballscrew, 2x 700mm Hiwin 15mm rails for X
1x 400mm 1610 ballscrew, 2x 400mm Hiwin 15mm rails for Z

overall dimentions 1330mm x 830mm (without gantry reinforcement, i expect 890mm after reinforcement) x 600mm
travell dimentions 840mm x 530mm x 250mm (only 180mm usable, that's more than enought for me)

On pictures subtitles:
red - steel tube 80x30mm with 3mm thickness
purple - steel tube 60x30mm with 3mm thickness
red - steel corner 50x50mm with 5mm thickness

the Z plate (attached to the X axis) is aluminum plate 15mm thick and has reinforcement/spacer for the linear rails 35mm width 20mm thick aluminum bar bolted with 8 screws on both sides. The spindle plate will be a nightmare to mount with that hertz spindle but I think I can manage to do it. it's 15mm thick I think that's enough isn't it?

well any doubts please ask.

hope it's ok now.

regards

[pippin88]

Good to see 10mm pitch screws and linear rails, you'll be happy with them.

Gerry was saying that the gantry (currently two separated beams) would be stiffer if made from a single large beam, or by adding a plate at front and back to secure the tubes together.

Gantry uprights will be a problem.
Do a good images search for commercial CNC routers and you'll see they use large box / square section uprights.
The uprights must be stiff in X Y and Z directions. Your design is not stiff in the Y direction (across the gantry)

Are your motors underneath? One of the advantages of dual drive is that you don't need the bar underneath joining the bottom of the gantry uprights. This allows support along the whole of the base not just the ends. Much stiffer. I would move the motors to the sides and get rid of the joining plate.

[vakeiros]

yes pippin I know, that's why I'll bolt some 80x40x3mm tube on the side of the uprights (what I've been calling Gantry pilars XD) This will make it stiff for sure!

soon I'll have the project complete on SW so you can see and tell me what you think after the changes.

thanks for the advice on the 10mm pitch ballscrews and linear rails

[vakeiros]

pippin, here's my idea now on pictures:





what do you think about this? I'm almost sure that this will make it at least stiff enough... doesn't it?

[vakeiros]

...

Are your motors underneath? One of the advantages of dual drive is that you don't need the bar underneath joining the bottom of the gantry uprights. This allows support along the whole of the base not just the ends. Much stiffer. I would move the motors to the sides and get rid of the joining plate.

don't know why but didn't read this part of your post... so are you saing that I should place one motor each side of the table up side? and what about the rails should they stay where they are or move them up too?

thanks for all

[gio666]

pippin, here's my idea now on pictures:





what do you think about this? I'm almost sure that this will make it at least stiff enough... doesn't it?

The way you have the steel on the uprights it wil nothing to very little . it will just put more force on the front bearing with no support. 15mm are very small blocks, far better to use at least 20mm .
Instead of adding steel to the upright, better to use thicker uprights and us backing plate to tie both uprights together .
The lower Crossmember adds a large amount of support for gantry section, To get maximum gain with dual Ballscrew if all possible add the lower part. turn the sideways compared to the way you have in sketch . Larger lower crossmber the better. should be around 80% of the width of uprights


XZero CNC Routers

[vakeiros]

Well I have been drawing a new version of the machine until now... than when I get back here to post gio666 posted some ideas. thanks for that... I'll go to bed now but I'll post here the new machine so please tell me what you think...

the X and Y guides on the draw are 15mm but I'll put 20mm on the machine (will make the due changes tomorrow), so if the steel on the uprights will do next to nothing how much thick should I get them (I don't quite agree with that statement but what do I know? XD)

in fact I was thinking about gettin 20mm uprights instead of 15 but I don't really.

so let's see what you guys think about the new design and I'll take point from there.

thanks for all the input!

[aarggh]

I'd remove the brackets along the top of the horizontal supports on the gantry, and instead bolt flat bar (as wide as you can get and fit it) right along the top of each, and into the gantry sides. You need as much right angle support as possible, as those brackets won't stop the gantry flexing.

For stiffening a machine, right angles, the larger the better, are your best friend!

Narrow angle supports do very little to counter flex.

Also, turn the spoilboard supports 90degrees, so the narrower side faces up, this will greatly increase the rigidity of the base. Again, right angles! Or another way you could do it is to add at least another red frame support halfway along the Y axis, from side to side, and then rest the purple spoilboard supports from the very back end to the front, so they rest on the three (at least 3) frame supports.

cheers, Ian

[vakeiros]

Hi guys, before all, wish you all happy holidays!

well I just start ordering the stuff to begin building my machine! already have most of steel and alluminum needed to do this and have my hiwin guides and ball screws on my way! I'd made some changes on the machine design in order to stiff the machine and decrease the height of the gantry uprights. when I get the guides, ballscrews and accessories I'll make a new defenitive design and post here, so before that I have another doubt and really need your experties.

I'm not going cheap on this machine and I started looking for Nema 34 motors instead of the 270oz nema 23 that I already own, so my question is, and I need a very honest answer:
Do you guys think the 270OZ motor are really enough or should I buy something like these guys? these are 1090oz nema34 with 3.5mH phase inductance... really need a straight answer here.

this machine will have 1200mm HIWIN 20mm guides on the X, 700mm HIWIN 20mm on Y, 400mm HIWIN 15mm on Z, double X motors, 1610 ballscrews on all axis and will attach a Hertz 2.2KW spindle on.

will have an extimated working area of: 880x530x200mm (the Z working area is still not well defined but it will be somewhere between 180-210mm)

so what do you guys say about the motors?

thanks for all the input and help!

[aarggh]

Unless your machine is going to weigh at least several hundred kilograms, and will also be sufficiently rigid to machine aluminium primarily, the larger motors will pretty much be wasted. 270oz/in is plenty strong for the size and weight machine your building.

My large 6090 machine is 300kg's, and uses 280-300oz/in steppers from memory, and they are more than adequate for any machining I do, including quite a lot of aluminium. Bigger steppers aren't always better.

cheers, Ian

[wizard]

One thing you might want to consider is the X axis table support rails (the purple rails) and the direction they run in. You might be better off on a light frame like this, turning them 90° so that the frame members actually supporting the X axis rails are better supported. The two members supporting the X axis linear rails appear to be rather skinny so stiffening them up might be helpful. The frame would take on the appearance of a ladder.

[vakeiros]

thanks for the input, forgot to talk about that. the purple rails that you are talking abou are gone. I took all your advices and used a 200x20mm aluminum bar across the gantry. then used 35x32mm aluminum bar bolted to that bar and the HIWIN guides will bolt to that 32x35 aluminum bar (these are both acting as spacers and reinforcing the gantry). don't know if you understood me but when I make the final project in solid works I'll post it here so you can see better.

regards